Hey, that Aiden Pearce guy. The jerk who keeps pulling his turtleneck over his mouth, breaking into systems and generally wreaking havoc all over Chicago. Somebody should try to stop him, no? Well, when you fire up Watch Dogs’ companion app on your phone, that somebody is you.

In Aiden Pearce’s hands, the smartphone in Watch Dogs makes him a super-powerful hacker, able to find out anything about anyone in the city of Chicago. In your hands, a real-world smartphone turns you into the cops, giving you the power to screw with the game’s data vigilante. I saw Watch Dogs’ CTOS app—named after the software system that automates the Second City in the game—running in a demo at PAX. It reminded me a lot of the asymmetrical multiplayer in ZombiU. Just like that other Ubisoft game, the player with the touchscreen—which offers a top-down view of the world map—is launching an array of forces at a single player using a gamepad.

For example, you can have a police helicopter shining a powerful spotlight on Pearce from high overhead or drop in cop cars to give chase. It all starts with the mobile player sending an invite to a console player on their friends list. (Still isn’t clear what friends list resource will be used for that, though.) All of the power of the CTOS system will be available to mobile players, so they’ll be able to use things like traffic barricades to impede their prey’s progress.

And the more chaos the console player causes, the more attacks unlock for the mobile player. If the person playing on an Xbox 360 is going around killing innocent pedestrians while trying to escape, his/her opponent on an iPad will be able to explode steampipes to blow up a carjacked ride or raise a bridge’s sections so Pierce can’t drive over it.

It was fascinating to watch the action unfold during the PAX demo, with actions input on an iPad happening almost instantaneously. At the end of a challenge, both players get cash and XP so there’s a good reason to grief your Watch Dogs-playing friends while commuting into work. Expect the CTOS app to be available when Watch Dogs comes out in a few weeks.